Abstract:Concrete is a very popular material in the construction industry-it is, however, susceptible to quasi-brittle failure and restricted energy absorption after yielding. The incorporation of short discrete fibers has shown great promise in addressing these shortfalls. A natural fiber such as sisal is renewable, cheap, and easily available. It has also exhibited good tensile strength and can significantly improve the performance of concrete. In this study, the physical and mechanical properties of sisal fiber-reinforced concrete were reported. Sisal fibers were added in the mix at percentages of 0.5%, 1.0%, 1.5%, and 2.0% by weight of cement. Physical properties measured are workability, water absorption, and density while mechanical properties reported are compression strength, split tensile strength, and static modulus of elasticity. The computed modulus of elasticity of sisal fiber-reinforced concrete was compared with predicted values in some common design codes. From the study, it was concluded that sisal fiber can enhance the split tensile strength and Young's modulus of concrete but cannot improve its workability, water absorption, and compressive strength.

Introduction: Fiber reinforced concrete is becoming popular in improving the quasi-brittle failure of concrete. Natural fibers such as sisal holds great promise in this regard. It has amazing tensile strength and is renewable. This paper presents the result of an investigation carried out on the effect of sisal fiber on the compressive strength, Split tensile strength, failure mode and Poisson ratio of Sisal Fiber-Reinforced Concrete (SFRC). Methods: A mix proportion of 1:1.92:3.68 and w/c ratio of 0.47 for a target compressive strength of 35 MPa was used. Sisal fiber was added at percentages of 0.5%, 1.0%, 1.5%, and 2.0% by weight of cement. The effect of specimen shape on the compressive strength of sisal fiber-reinforced concrete (SFRC) was reported. The compressive strength of cube (150mm X 150mm) and cylinder (150mm diameter and 300mm height) specimen was determined at 7 and 28 days, while Split tensile strength and Poisson ratio were obtained using cylindrical specimen (150mm diameter and 300mm height). Results and Conclusion: The result shows that the addition of sisal fiber slightly reduces the compressive strength of concrete, increases its split tensile strength up to 47.167% of the control specimen, arrests crack propagation and reduces its Poisson ratio. The correlation between the compressive strength of cylindrical and cube specimen was established with a ratio ranging between 0.82 - 0.73. The difference in the compressive strength was found to increase with rise in the percentages of sisal fiber. Based on the ratio and mechanical properties, 1.0% sisal fiber content was recommended as the optimum for reinforcing concrete.

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